The preferred embodiment of the invention concerns a method for controlling an electrophotographic printer or copier that has at least one developer station for development of a latent charge image on a photoconductor with toner. It also concerns a control device for such a printer or copier.
Known methods of the aforementioned type typically provide different operating states or operating modes that the printer or copier can adopt in operation. Examples for such operating states are a standby mode in which the functional voltages and currents of the developer stations that are necessary for developing of charge images are typically deactivated and the mechanical actuators of the developer station are stopped. Such a standby mode is typically adopted when the printer or copier is turned on but no print data is present.
A further typical operating state is the print operation mode in which typically all functional voltages and currents of the developer stations are switched to nominal parameters and all actuators run with nominal parameters. Such a print operation mode is typically started as soon as print data are present and is maintained as long as the print data are present. During this print operation, as stated the actuators of all developer stations run in normal operation, meaning that all mixing devices (such as bucket wheels, paddlewheels, mixing dredgers and the like) for stirring the developer and all devices for applying the developer from the developer station onto the photoconductor are in operation during the print operation mode.
During such a print operation it can occur that one or more developer stations has only a very small toner discharge or even no toner discharge at all for a longer time period. In the present document, either a mixture of toner and carrier particles or a one-component developer is meant with the term “developer”. In the case of the one-component developer, the terms “developer” and “toner” designate the same thing. The case of slight or disappearing toner discharge occurs relatively frequently in color printers or copiers in which a separate developer station is provided for each color component (cyan, yellow, magenta and black) and in fact when the print data do not contain a color component or contain a color component to only a limited extent for a longer time period. A prolonged low toner discharge can, however, also occur in one-color printers, namely when a plurality of successive print pages with little content is printed.
It has been shown that the developer ages or is damaged relatively quickly with prolonged low toner discharge, i.e. wears in the developer station and leads only to poor print results. In the case that a developer station is not required for a longer time period during the print operation, it is itself additionally subjected to an unnecessary wear.